Reconfigurable metamaterial

Abstract

A reconfigurable metamaterial formed of an assembly of building blocks including first rigid members hingedly engaged together at a first hinge, and second rigid members hingedly engaged together at a second hinge. The first rigid members are hingedly connected to respective ones of the second rigid members at third and fourth hinges. The third and fourth hinges are offset from the first and second hinges. A first elastic member is engaged to the first rigid members and biases them away from one another. A second elastic member is engaged to the second rigid members and biases them away from one another. The assembly has a deactivated configuration, wherein the third and fourth hinges are spaced apart, and an activated configuration, wherein the third hinge merges into the fourth hinge to create a contact-induced metahinge about which the first rigid members pivots relative to the second rigid members.

1 . A reconfigurable metamaterial, comprising:
 an assembly of building blocks secured to one another, a building block of the building blocks having:
 first rigid members hingedly engaged to one another at a first hinge; 
 second rigid members hingedly engaged to one another at a second hinge, each of the first rigid members hingedly connected to a respective one of the second rigid members at a respective one of a third hinge and a fourth hinge, the third hinge and the fourth hinge being offset from the first hinge and the second hinge; 
 a first elastic member engaged to the first rigid members and biasing the first rigid members away from one another; and 
 a second elastic member engaged to the second rigid members and biasing the second rigid members away from one another, 
   wherein the assembly has a deactivated configuration in which the third hinge and the fourth hinge are spaced apart from one another and has an activated configuration in which the third hinge merges into the fourth hinge to create a contact-induced metahinge about which the first rigid members pivot relative to the second rigid members.   
     
     
         2 . The reconfigurable metamaterial of  claim 1 , wherein the building block has a first symmetry plane intersecting both of the third hinge and the fourth hinge. 
     
     
         3 . The reconfigurable metamaterial of  claim 2 , wherein the building block has a second symmetry plane intersecting both of the first hinge and the second hinge. 
     
     
         4 . The reconfigurable metamaterial of  claim 1 , wherein, in the deactivated configuration, the first rigid members and the second rigid members are spaced apart from one another by a spacing angle (2α) defined from one of the first rigid members to the other of the first rigid members around the first hinge, the first rigid members and the second rigid members having a geometry incompatibility angle (β) defined from the one of the first rigid members to a plane intersecting both of connections defined between the first rigid members and the first elastic member around one of the connections, wherein the spacing angle is smaller than two times the geometry incompatibility angle, the building block being monostable. 
     
     
         5 . The reconfigurable metamaterial of  claim 1 , wherein, in the deactivated configuration, the first rigid members and the second rigid members are spaced apart from one another by a spacing angle (2α) defined from one of the first rigid members to the other of the first rigid members around the first hinge, the first rigid members and the second rigid members having a geometry incompatibility angle (β) defined from the one of the first rigid members to a plane intersecting both of connections defined between the first rigid members and the first elastic members around one of the connections, wherein the spacing angle is greater than four times the geometry incompatibility angle, the building block being bistable. 
     
     
         6 . The reconfigurable metamaterial of  claim 1 , wherein the first rigid members and the second rigid members are triangles. 
     
     
         7 . The reconfigurable metamaterial of  claim 1 , wherein the first elastic member and the second elastic member include a pair of first flexible beams and a pair of second flexible beams, the first flexible beams fixedly interconnected to one another at first proximal ends and each ending at first distal ends each connected to a respective one of the first rigid members, the second flexible beams fixedly interconnected to one another at second proximal ends and each ending at second distal ends each connected to a respective one of the second rigid members. 
     
     
         8 . The reconfigurable metamaterial of  claim 7 , wherein the building blocks are interconnected to one another to form a plurality of groups each including three building blocks, the three building blocks distributed around a central axis, the first proximal ends of the first flexible beams of each of the three building blocks of a group of the groups being fixedly connected to one another. 
     
     
         9 . The reconfigurable metamaterial of  claim 8 , wherein the groups are interconnected to one another to form a honeycomb structure. 
     
     
         10 . The reconfigurable metamaterial of  claim 7 , wherein the building blocks are interconnected to one another to form a plurality of groups each including four building blocks, the four building blocks distributed around a central axis, the first proximal ends of the first flexible beams of each of the four building blocks of a group of the groups being fixedly connected to one another. 
     
     
         11 . The reconfigurable metamaterial of  claim 10 , wherein the groups are interconnected to one another to form a matrix structure including a plurality of lines and columns. 
     
     
         12 . A building block for a metamaterial, comprising:
 first rigid members hingedly engaged to one another at a first hinge;   second rigid members hingedly engaged to one another at a second hinge, each of the first rigid members hingedly connected to a respective one of the second rigid members at a respective one of a third hinge and a fourth hinge, the third hinge and the fourth hinge being offset from the first hinge and the second hinge;   a first elastic member engaged to the first rigid members and biasing the first rigid members away from one another; and   a second elastic member engaged to the second rigid members and biasing the second rigid members away from one another,   wherein the building block has a deactivated configuration in which the third hinge and the fourth hinge are spaced apart from one another and has an activated configuration in which the third hinge merges into the fourth hinge to create a contact-induced metahinge about which the first rigid members pivot relative to the second rigid members.   
     
     
         13 . The building block of  claim 12 , wherein the building block has a first symmetry plane intersecting both of the third hinge and the fourth hinge. 
     
     
         14 . The building block of  claim 13 , wherein the building block has a second symmetry plane intersecting both of the first hinge and the second hinge. 
     
     
         15 . The building block of  claim 12 , wherein, in the deactivated configuration, the first rigid members and the second rigid members are spaced apart from one another by a spacing angle (2α) defined from one of the first rigid members to the other of the first rigid members around the first hinge, the first rigid members and the second rigid members having a geometry incompatibility angle (β) defined from the one of the first rigid members to a plane intersecting both of connections defined between the first rigid members and the first elastic members around one of the connections, wherein the spacing angle is smaller than two times the geometry incompatibility angle, the building block being monostable. 
     
     
         16 . The building block of  claim 12 , wherein, in the deactivated configuration, the first rigid members and the second rigid members are spaced apart from one another by a spacing angle (2α) defined from one of the first rigid members to the other of the first rigid members around the first hinge, the first rigid members and the second rigid members having a geometry incompatibility angle (β) defined from the one of the first rigid members to a plane intersecting both of connections defined between the first rigid members and the first elastic members around one of the connections, wherein the spacing angle is greater than four times the geometry incompatibility angle, the building block being bistable. 
     
     
         17 . The building block of  claim 12 , wherein the first rigid members and the second rigid members are triangles. 
     
     
         18 . The building block of  claim 12 , wherein the first elastic member and the second elastic member include a pair of first flexible beams and a pair of second flexible beams, the first flexible beams fixedly interconnected to one another at first proximal ends and each ending at first distal ends each connected to a respective one of the first rigid members, the second flexible beams fixedly interconnected to one another at second proximal ends and each ending at second distal ends each connected to a respective one of the second rigid members. 
     
     
         19 . A reconfigurable metamaterial, comprising:
 an assembly of building blocks secured to one another, a building block of the building blocks having:
 a first pair of first rigid members extending from first proximal ends to first distal ends, the first rigid members pivotably engaged to one another at the first proximal ends to define a first hinge; 
 a second pair of second rigid members extending from second proximal ends to second distal ends, the second rigid members pivotably engaged to one another at the second proximal ends to define a second hinge, each of the second distal ends pivotably engaged to a respective one of the first distal ends to define a respective one of a third hinge and a fourth hinge; 
 a first elastic member secured to both of the first rigid members, the first elastic member exerting a moment about the first hinge opposing a rotation of the first rigid members towards one another; 
 a second elastic member secured to both of the second rigid members, the second elastic member exerting a moment about the second hinge opposing a rotation of the second rigid members towards one another; and 
   wherein the assembly has a deactivated configuration in which the third hinge and the fourth hinge are spaced apart from one another and has an activated configuration in which the third hinge merges into the fourth hinge to create a contact-induced metahinge about which the first pair of the first rigid members pivot relative to the second pair of the second rigid members.   
     
     
         20 . The reconfigurable metamaterial of  claim 19 , wherein the building blocks are interconnected to one another to form one or more of a matrix structure and a honeycomb structure.